1. Field:
The field of the invention is endless track assemblies for snow grooming vehicles, and more particularly the cleat assemblies thereof, including structures for fastening the cleats to the flexible plastic belting of such tracks.
2. State of the Art
Snow groomer vehicles use endless tracks made up of flexible plastic belts made continuous by lacing their ends together. Actual lacing thread my be used, although lacing joint assemblies are more commonly employed, being a combination of metallic hinge plates and an associated hinge pin. The snow grooming vehicle commonly has an endless track assembly on each of its sides, each comprising a number of fabric reinforced plastic belts. The belts are spaced apart to provide a broad base for the track while utilizing minimum amounts of belting. Steel cleat assemblies are bolted across the individual belts at intervals, tieing them together into a track assembly. Each assemblied track is engaged by a power-transmitting sprocket wheel, which forces the belts to travel together around a set of guiding wheels called bogies. The powered belt imparts horizontal shear forces to the cleats, which engage the snow to propel the vehicle. Extensive development has gone into the design of the elongate cleat members, with the objectives of providing maximum forward traction, along with substantial resistance to side slipping. Cleat constructions are disclosed in U.S. Pat. Nos. 3,765,731, 4,560,211, 4,281,882 and 4,059,315. Typically, the ground contacting cleat, also called a "grouser", is fastened to the outside of the flexible belting by bolts installed in matching holes in the grouser, the belt, and a metal backing plate on the inside of the belt. A large number of bolt and nut assemblies are required, so that cleat assembly is quite time consuming. Further, at least two assembly workers are required, because bolt heads and nuts, on opposite sides of the belts, cannot be reached simultaneously by a single individual. The large number of bolt assemblies is required to exert the shearing forces against the belt holes, even though dimpled belt grabber plates may be employed between the grouser and the belt. See U.S. Pat. No. 5,033,801. Not only is the initial assembly time consuming, but cleat replacement is often necessary because of bolt or grouser failure. This is especially difficult in the field, and generally requires returning the vehicle to a maintenance and repair shop. Prior art grouser designs are seriously weakened to provide an open side for bolt and nut access, exacerbating the breakage problem. (Prior Art FIG. 11)
Some prior art cleat designs have attempted to deal with the problem of handling a large number of separate cleat retaining nuts by welding or otherwise fastening the nuts directly to the grouser plate, such as by welding. These have generally proven unsatisfactory. Welding of the nuts on the hardened cleat material tends to create a problem with loss of hardness in the critical nut and bolt area. Further, breakaway of welded nuts is a common problem. If the attachment of the nuts to the grouser is effective and permanent, a further problem exists in that the damage to a single nut, as by cross threading or the like, then requires replacement of the entire grouser-nut assembly.
A cleat assembly design of greater strength is needed, capable of installation and replacement by a single person.